1. Field of Invention
The present invention relates to a depth stop device for setting a desired drive-in depth for a to-be-driven-in fastening element that is driven in by a motor-driven screw driving tool, and mountable on a nose member of the screw driving tool housing which is connected with a working tool holder for joint rotation therewith. The depth stop device includes an adjusting ring rotationally mountable on the nose member of the tool housing with a connection sleeve that can be formed as a separate member or as a part of the tool housing. The depth stop device further includes a substantially sleeve-shaped depth stop displaceable in an axial direction relative the connection sleeve by rotation of the adjusting ring, means for rotationally securing the adjusting ring on the connection sleeve until an adjusting torque in a rotational direction is applied to the adjusting ring by a screw driving tool user, and means for securing the adjusting ring on the connection sleeve in the axial direction.
2. Description of Prior Art
Depth stop device of the type described above are used for preliminary setting, in a known manner, of a maximal drive-in depth of a fastening element, such as, in particular, a screw that is being driven in workpiece by a screw driving tool. Upon reaching a predetermined depth, the torque transmission from the motor to the chuck is usually interrupted by separation of a friction clutch. The depth stop device is removable from the screw driving tool in order to be able to use the screw driving tool without the depth stop device or in order to replace a screw bit.
U.S. Pat. No. 5,380,132 discloses a depth setting system for a power-driven screw driving tool in which the adjusting ring has, at its end remote from the working tool, two resilient hook elements. Upon mounting, the hook elements snap behind a circumferential rib formed on the screw driving tool housing. On the circumference of the adjusting ring, there are provided a plurality of indentation which engage, in a plurality of rotational positions of the adjusting ring relative to the housing, respective elevation provided on a nose member that is screwed to the housing.
With the above-described design of the depth setting system, the axially and rotationally securing means is formed essentially by different resilient elements of the adjusting ring and which cooperate with respective correspondingly formed, shaped elements.
The drawback of the known depth setting system consists in that the adjusting ring has a very expensive construction due to a large number of resilient elements formed thereon. In addition, the repeated engagement of the indentation of the adjusting ring with the elevation of the nose member leads to excessive wear of these elements, which results in a relatively short service life of the rotationally securing means.
Accordingly, the object of the present invention is to provide a depth stop device in which the drawback of the prior art device are eliminated.
Another object of the present invention is to provide a depth stop device that would insure a stable axial locking of the depth stop at a releasable mounting of the device on the screw driving tool and a rotational locking of the depth stop for a reliable setting of the preset position of the depth stop relative to the screw driving tool housing.
A further object of the present invention is to provide an easily mountable depth stop device that has reduced manufacturing costs.